Hey guys, I was reading today that using an intake with the rear water ports will help keep the heads cooler, avoid hot-spots, and less likely to crack heads or pop head gaskets.

My old '87 Camaro with a factory Q-jet setup had this type of intake (aluminum).

I was wondering if it might be a good idea with the new 418 stroker SBC I am building. I will be using aftermarket aluminum heads with thick decks, so cracking shouldn't be an issue with them. However, it seems like a good idea in general, especially on a 400.

What do you guys think? Worth it to have rear cooling or worthless to begin with?

Thanks in advance!!

Cable, I don't know what you should take from this, but I run 30 year old GM alloy heads without the passage, and never had any issue associated with it.

Originally posted by 427L88:
Cable, I don't know what you should take from this, but I run 30 year old GM alloy heads without the passage, and never had any issue associated with it. Me too, but never a 400 block. I just thought it might be helpful in preventing problems that 400's are known for.

Where's DZ!?

Cable,
Good plan smile.gif
We do it on almost all our circle track engines & also on a lot of street 400 stuff without steam holes on the bowtie & aftermarket blocks. Works great, keeps from having to get all that hot water out of those two small passages in the front of the intake.
Plus it looks really cool ;)
I also add water from the pump to the center of the block for the circle track stuff
I always put steam holes in the center on stock blocks for the street as you can get hot spots behind the head bolts that will not show up on a temp guage.
The end cylinders are not as prone to the steam problem because you do not have two exhaust ports next to each other.
The aftermarket blocks don't have the same problem as the bolt holes are blind so it's much smoother around the bores.
CV Products makes a spacer that goes under the water neck with two 3/8 NPT holes to run the lines to so you still have the fitting in the front of the intake for temp sensors heaters etc.

No we don't run heaters on the circle track stuff :D

Does anyone have a picture showing how to plumb this configuration? Thanks!

Cable,

I haven't done this myself, but have seen alot of Circle Track motors with this done. Actually there is a photo of a motor with this done on the cover of the new Circle Track magazine. I would be interested to see what Jack aka 'HOTRODSRJ' over in the cooling section would say about this. Maybe you should link this thread over there and post it to his attention.

Since I provided an illustration than would have led to possibly bum advice..DONE!

Complete with a misspelling! (http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=27;t=001224)

There certainly wouldn't be anything wrong with water outlets at the rear of the heads. But, of course, you have to have plumbing running from the rear corners of the intake manifold to the front to allow the water to pass to the radiator. This would probably be beneficial for a full race motor, or, even a heavily modified street motor. But, normally, for a regular street/performance motor, I don't know if the benefit would outweigh the expense/trouble. Even on the race engines which we used to have years ago (back in the Civil War days) we never contemplated doing this. Never had any cooling problems. I'm not saying don't do it, I'm just saying I never felt that the extra water flow was worth the effort on our engines.

theres a pic on my site on page 2 of how i did it. although i have know run the lines under the intake (super victor). here my experiance with the 4 corner so far. the intake is plumbed with 3/8 npt. by the time you get a fitting with a hose there is very little water going to go through. my lines are plumbed down stream of the thremostat. one would think that as the engine warmed up (thremostat closed) the water passing through the small lines on the other side of the thermostat, the warmer water would heat the sender and indicate a rise in temp at the gauge before the ther. opened. sometimes this happens sometimes i get a really quik rise in temp when the therm. opens. this indicates to me that THERE is very little water going through. BUTTTT, as the water gets hotter and gases are formed and rises to to top of the engine, it know has a place to go and not be trapped in the head...... I THINK. hope this helps Dave

I don't think you have to run the rear feeds to do a good cooling job anymore with the 400s or any motor for that reason. Yes the 400 is more difficult because of the siam cylinder design and the rear feed would help that then. This design was invented because the coolant distribution system of a block and heads or "coolant manifold" as it's called, is essentially like a "soaker" lawn sprinkler. The holes and passages nearest the water pump always have the greatest pressure and flow....just like turning on that soaker hose and seeing the water barely dribble out the end...but strong at the hose feed.

The very same thing happens in your coolant manifold and as you move rearward the pressure and flow drop and thus cooling capacity is compromised. But, that was with yesterday's waterpump technology and that was and is still very poor when compared to the high flowing aftermarket pumps of today.

Therefore a good Stewart or TuffStuff high flowing water pump is just the ticket and I predict that you will do just fine! Most of these aftermarket water pumps provide 150% of the flow AND pressure at these critical spots...so the worry goes away. Running "overdrive" technology pulleys will also improve the situation. Iwould also run a "surfactant" such as WaterWetter that aids in air expulsion in the system and actually sucks up heat faster (but not more). Combined that high flowing water pump with a high flowing thermostat such as a Mr Gasket, and of course lots of airflow and you will be a cool Chevy...pun intended graemlins/thumbsup.gif

While I do agree they are not a necessity I can tell you from experience on siamised blocks & higher HP engines that the rear coolant lines help in circle track & or endurance applications.
Not only can they help the engine run cooler, I believe they also tend to help even out overall temps.
They are also very simple to install on almost all aftermarket intakes now as most are set up for the lines.
I also agree completly with using Stewart pumps & thermostats (actually Robert Shaw). Been a dealer for them for a number of years & feel they are an excellent pump. graemlins/thumbsup.gif

Here's some interesting reading from Stewart: http://www.stewartcomponents.com/html/tech_support/techtip5.asp

We needed to run the rear lines on our destroked 400 with massaged Vortec heads. (Circle track) Even turning 7200rpm didn't move enough water into the rear of the heads to keep them cool.

Rules required the use of a stock iron manifold, so we just drilled and tapped the manifold, installing 1/2" elbows, and connecting braided lines.

Presto - Chango! Nice and cool now.

I can understand why you would want extra cooling with racing being the subject, but for the street I don't believe they are necessary. I know of at least a few 400s on the street in excess of 500hp without rear feeds and keep cool with high flowing pumps and so forth.

But there is no harm in the extra feeds tho...just kinda complicated looking to me?

I like the idea of cooling 5 & 7 a little, as they fire consecutively.

Digging up my old post....

I am looking to buy Pro-Products 'Hurricane' single plain intake for this motor, it has the rear cooling ports built in already. They look like they are at least 1/2" pipe. I might as well use them!! :D

http://images.racepartsdirect.com/satinhurricane.JPG

I've got them on my siamesed BB manifold as well. I often wondered if they were worth the effort. If there isn't any detrimental effects, I think I'll go ahead and plumb them.

John

I don't want to hijack this thread, but is it common for the #5 cylinder to run hotter than the others on a BB? Mine seems to and I think I remember reading that somewhere. If that's true, would it also apply to #4?

Von, it's my understanding that the 5/7 run hotter because they are further from the water pump than #4. I think one of the purported benefits of the 4/7 swap is to move the adjacent firing closer to the water pump.

I'm curious what the cooling benefits will be because my new sheetmetal intake has no thermostat housing so I am planning on running a 4 to 1 manifold with -12 lines from all 4 corners feeding it directly to my rad hose. I will make restrictors that I can put in the fittings so that I can put more backpressure on the flow out of the heads if necessary as I will have no thermostat.

I know that all the big inch Pat Musi engines I have seen run these 4 to 1 manifolds so there must be SOME advantage to getting the hot water out of the back of the block. Probably a detonation preventer.

Originally posted by 66 283:
I'm curious what the cooling benefits will be because my new sheetmetal intake has no thermostat housing so I am planning on running a 4 to 1 manifold with -12 lines from all 4 corners feeding it directly to my rad hose. I will make restrictors that I can put in the fittings so that I can put more backpressure on the flow out of the heads if necessary as I will have no thermostat.

I know that all the big inch Pat Musi engines I have seen run these 4 to 1 manifolds so there must be SOME advantage to getting the hot water out of the back of the block. Probably a detonation preventer. Ryan,
Just my opinion , but I think one of the biggest benefits that everyone seems to overlook when posting how it doesn't do any good & "mine works so it ain't necessary" or too much trouble etc,,, is with the four corner deal you no longer force all that hot water to pass completely through the already hot head from rear to front instead of removing it from the back & returning it to the radiator.
In my limited understanding of cooling, if you run hotter water over an already hot surface it isn't going to cool as well but maybe that's to simple :D

Anyway, I have used -6 or -8 lines, usually -8 & it seems to help noticeably on endurance stuff or street aftermarket small blocks with cooling.

This in turn as you said should help in controlling detonation,, except in the case of a limited HP deal like yours :D

I once worked for a car company that still used inline 6 engines with coolant that flowed from the front of the block to the rear and then up into the head at the rear. Then the flow through the head was from the back to the front. The #1 cylinder had the hottest water around the combustion chamber which resulted in more knock on that cylinder and a measurable increase in wear on the exhaust valve seats compared to the rear cylinders. So, it would seem that the plumbing on the rear corners should help even out things a bit.

I was having troubles in hot climate keeping my engine cool. It was mostly an airflow problem because as I drove faster it would drop the temp significantly. It's ok on a typical day in my home town, even in bumper to bumper traffic.

My new electric pump moves 60+ gpm (probably rated at zero pressure :rolleyes: ) and my spal fan is rated at about 2400 cfm - I might have to slow down the flow a bit with some backpressure to keep it from cavitating, was also going to the 4 corner to 1 manifold trick since the manifold doesn't have a thermostat housing, and adding another fan and making a shroud for about 4000cfm.

That would do it, wouldn't you think Wolfplace?

But I'm adding a point of compression and removing 10 deg @ .050" on the camshaft so god only knows what my DCR is now! ?! LOL Oh ya, my block is half filled now too so I'll need an oil cooler. :D

Originally posted by 66 283:
I was having troubles in hot climate keeping my engine cool. It was mostly an airflow problem because as I drove faster it would drop the temp significantly. It's ok on a typical day in my home town, even in bumper to bumper traffic.

My new electric pump moves 60+ gpm (probably rated at zero pressure :rolleyes: ) and my spal fan is rated at about 2400 cfm - I might have to slow down the flow a bit with some backpressure to keep it from cavitating, was also going to the 4 corner to 1 manifold trick since the manifold doesn't have a thermostat housing, and adding another fan and making a shroud for about 4000cfm.

That would do it, wouldn't you think Wolfplace?

But I'm adding a point of compression and removing 10 deg @ .050" on the camshaft so god only knows what my DCR is now! ?! LOL Oh ya, my block is half filled now too so I'll need an oil cooler. :D =
I would certainly expect it to. I ain't to sure on the waterpump though. 60GPM sounds like a lot but I think you are right on the ratings.
Go over here & do some reading & if you have any questions call Jack or post to him. He is a super nice guy & knows cooling systems pretty well.
Stewart Site (http://www.stewartcomponents.com/cgi-bin/yabb/YaBB.cgi?board=tech)

It is not your typical electric - it's the high volume version, the big billet one from CSR and they quote 70+ but that's at 16V, they quote 60 at 12V so it's somewhere in between at 14V.

It is probably rated at no backpressure but if you compare it's free flow against other electrics it's double the volume.

I have posted on stewarts site before - his mechanical pump works great, I have one, but I need electric for these race deals where you have to cool off and make back to back runs.

Ryan,

This in turn as you said should help in controlling detonation,, except in the case of a limited HP deal like yours :D [/QB][/QUOTE]


:D :D :D

I would tell you what my DCR is and what desktop dyno says but then I'd have to kill you. HA HA HA!! :rolleyes:

Let's just say I have increased my CR and downsized the cam and have two foggers on 93 octane so you wouldn't want to know my DCR is. If I told ya you would tell me to retard the cam 720 degrees.

Originally posted by 66 283:
I would tell you what my DCR is and what desktop dyno says but then I'd have to kill you. HA HA HA!! :rolleyes:

Let's just say I have increased my CR and downsized the cam and have two foggers on 93 octane so you wouldn't want to know my DCR is. If I told ya you would tell me to retard the cam 720 degrees. =
I think you should,, ummm retard the cam,, yeah,, that's it ,,,,, :D :D

But seriously, I think 720 is a little too much.
I redid your numbers & I only come up with 72 degrees,,, you must have misplaced a decimal :( :D